Word-learning abilities in deaf and hard of hearing preschoolers: Effect of lexicon size and language modality.

Directions:

Dr. Amy Lederberg/Georgia State University, GAand Dr. Pat Spencer/Gallaudet University, Washington, D.C.were available from 2/23/09 until 3/8/09to answer questions and share ideas concerning their research and its implications for parents of children who are deaf/hard of hearing, their teachers and other professionals who work with them.

You are encouraged to read the research summary below and review the attached discussion.

Abstract
It has been widely observed that children who are deaf or hear-of-hearing tend to have smaller vocabularies than hearing children.This not only gives evidence of delayed language development, but it can interfere with their acquiring literacy and academic skills.In many cases readers with hearing loss do not just have to learn how a word is represented in print, they must learn the meaning of the word at the same time.Thus vocabulary development is an important area of research and programming for deaf and hard-of-hearing children.This study examined deaf and hard of hearing (DHH) children’s ability to learn new words. Ninety-eight DHH 2-to 6- year-olds were assessed with two word learning tasks. The children showed three levels or stages of word-learning abilities. Twelve children were not able to learn new words quickly. Thirty-six children learned new words quickly but only when the researcher clearly indicated their meaning. Forty-nine children learned new words quickly even when they had to infer the meaning of the word through a strategy called novel mapping. These abilities were more strongly related to the number of words the children knew than to their chronological age. The results show that DHH children develop word learning abilities that are similar to hearing children with similar vocabulary size. However, for some of the deaf or hard-of-hearing participants, the acquisition of these abilities was delayed as long as 3 years.The tasks used in this study can be used to assess the type of input an individual child needs to acquire new words easily, and thus can assist in designing optimal word-learning activities.

Summary Researchers have shown that hearing children’s ability to learn new words typically changes dramatically between 1 and 2 years of age. Initially children only acquire words for objects or events that they find interesting and that are repeatedly labeled by others. During this slow learning phase, children may only acquire one new word a week.Around 18 months a dramatic change occurs. First, typically-developing children gain at least an initial understanding of a new word after hearing it a few times.This is called “fast-mapping.”Second, children become very good at learning the meaning of a new word when adults explicitly use social cues (like pointing) to indicate its meaning (for example., learning “gorilla” after mom says “gorilla” while pointing to its picture). Another dramatic change happens around age 2-1/2 or 3 years when typically-developing hearing children no longer need adults to directly indicate the meaning (or “referent”) of a new words. Instead, a child is able to figure out or “infer” the meaning of a word from its context. This is especially effective when the word for only one object in the context is unknown to the child. To illustrate, if a child is looking at a lion, an elephant, and a gazelle, and an adult says, “Oh look, a gazelle” (without pointing) the child who already knows “elephant” and “lion” will assume “gazelle” refers to the novel animal. Surprisingly, 3-year-old hearing children’s acquisition of words learned through such indirect processes is as robust as when an adult directly and explicitly indicates the meaning of a word. These progressively advanced stages in word learning abilities allow the rapidly accelerating development of vocabulary knowledge that is typical for hearing children during toddler and preschool years.Research Procedures. The current study was conducted to explore whether DHH children develop these word learning abilities given the generally less complete or consistent language input that they receive. We tested 98 DHH children, ranging from 27 to 82 months old, drawn from 12 schools in five states. About a third of the children were in oral classrooms; the rest were in classrooms that used simultaneous or sign/bilingual language approaches. Twenty-three of the children had cochlear implants. Six of the children had deaf parents and were exposed to ASL from birth.All testing was conducted in the language system used in the child’s classroom.
In addition to two direct tests of receptive vocabulary, teachers completed a vocabulary checklist (MacArthur Communication Development Inventory) to estimate each child’s vocabulary size.The children also participated in two word-learning tasks:the first tested their ability to learn a new word or sign for a novel object when the relation between word/sign and object was pointed out explicitly; the second tested the same ability when the object the new word or sign represented had to be inferred.Each task exposed the child to four new words (total of eight words) that were “nonce” or newly created just for this assessment.That is, the created words or signs were possible but non-existent vocabulary items in the language system used with the child.Examples of the procedures for testing word learning are described below:

Results.We discovered that the age of the few deaf children with deaf parents in the study was linked strongly to the number of words they learned in the two tasks.(This is what would be expected from typically-developing hearing children.)This was not the case, however, for the majority of the DHH children.Their ability to learn the nonce words/signs in the tasks related strongly to their vocabulary size but not to their age.By continuing to collect information from a sub-group of the original participants, we were able to show that DHH children’s development of word-learning abilities paralleled that of hearing children—but most of the deaf children reached each stage at a much later age.In our DHH group, 12 children were not able to consistently learn the nonce words in either task.Another, much larger, group of DHH children learned words/signs with only three repetitions—that is, they learned to “fast map” new words in the direct reference task.However, they were not able to learn words/signs in the “novel mapping” task.Yet a third group was able to learn words in each type of task—that is, they showed “novel mapping” abilities.However, even the most advanced group learned new words or signs easier in the direct reference task (where the link with the object was explicitly made) than in the novel mapping task where the correct object had to be inferred. Implications.This study showed that DHH children who are of the same age can bring very different abilities to the task of learning new words. The results also suggested that it may be effective to explicitly indicate the meaning of new words and signs for DHH children longer than is the case for hearing children.
We believe that assessments of word-learning abilities using tasks like those in our study may be particularly important for children whose language skills lag behind their general cognitive skills or chronological age. Adults naturally increase cues to explicitly link objects with new words or signs (such as repeating the words and pointing to an object while talking about it) when communicating with infants and young toddlers. However, older language-delayed DHH children who are still in early stages of word learning may not be automatically provided these contextual supports even though they continue to be needed.Although support for vocabulary development should always occur in meaningful situations, an individual child’s need for more emphasis on direct indication of the meaning or the referent of a new word will become obvious in his or her response to the tasks we have summarized above.Tailoring language-learning experiences to individual needs can be expected to accelerate vocabulary development and, in turn, provide a better foundation for later, higher-level language and literacy skills.